Short fragment homologous replacement to provide BSE resistant cattle

ABSTRACT

A method for generating cattle resistant to Bovine Spongioform Encephalopathy through targeted alterations in the PrP gene is disclosed. The PrP gene of a cultured cells is altered to prevent its translation or to encode a dominant disease-resistant form of the protein, and the nucleus of the altered cell is used to clone a founder animal. In one embodiment, a single-stranded DNA fragment containing the alteration is used in single-stranded short fragment homologous replacement to alter the PrP gene.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. Provisional Application No. 60/373,149, filed Apr. 17, 2002, the disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] The modification of the genome of a cell can, in principle, be accomplished either by introducing a complete gene into the genome at a random position or by making a specific alteration in an existing, naturally occurring gene. In mammalian cells, endogenous enzymes that effect homologous recombination have been used to introduce disruptions in specific genes for more than a decade. The technique is termed homologous-recombination dependent gene targeting (hrdGT). Doetschman, T., et al., 1987, Nature 330, 576-78; Thomas K. R. & Capecchi, M. R., 1987, Cell 51, 503-12. These efforts involve the introduction of large pieces (several kilobases (kb)) of duplex DNA into the cell in the presence of a genetic selection system that distinguishes between homologous recombination and random insertion.

[0003] The use of an alternative has been described in mammalian cells. The technique is termed single-stranded short fragment homologous replacement (ssSFHR). A DNA fragment of intermediate size, typically 400 to 800 bp, is manufactured by excision from a plasmid vector or, alternatively, synthesized by PCR from a template. The short fragment is denatured by heat and the complementary strands can be optionally purified from each other. The technology is described in U.S. Pat. No. 6,010,908 by D.C. Gruenert, and in the scientific literature. Kapsa, R., et al., 2001, Human Gene Therapy 12, 629-42 (repair of murine dystrophin, unseparated strands); Colosima, A., et al., 2001, Mol. Therapy Vol. 3, No. 3 (episomal DNA in mammalian cells, unseparated strands); Goncz, K. K., et al., 1998, Hum. Mol. Genetics 7, 1913-19 (human cystic fibrosis transmembrane conductance regulator (CFTR), unseparated strands); Kunzelman, K., et al., 1996, Gene Therapy 3, 859-867 (murine CFTR, unseparated strands). The ssSFHR technique differs from hrdGT in several respects. The nucleic acid is shorter (400-800 nt) compared to several kb for hrdGT; in ssSFHR, the exogenous polynucleotide is denatured, i.e., single stranded, but is homologous with the target gene except for a few mutator nucleotides; in hrdGT, foreign genes are embedded in the exogenous nucleic acid; and, in hrdGT, a selection system is employed that distinguishes between homologous and illegitimate recombination, where in ssSFHR no such selection is required because illegitimate recombination does not occur at rates comparable to that of homologous recombination.

[0004] The present invention concerns the use of ssSFHR to modify the genome of cattle so that they are resistant to Bovine Spongioform Encephalopathy (BSE). BSE is a type of the so-called transmissible spongioform encephalopathies (TSE), which include ovine scrapie and human Creutzfeldt-Jakob Disease (CJD), as well as other diseases. A recent epidemic of over 170,000 cases of BSE occurred in the United Kingdom, which resulted in transmission of at least 130 cases to humans. The epidemic is believed to have been caused by the use of scrapie-infected sheep in the preparation of processed animal feed for the cattle, a process that was discontinued in 1988 and resulted in the reduction of the numbers of cases. Pattison, J., 1998, Emerg Infect. Dis. 4, 390-4; Nathanson, N., et al., Am. J Epidemiol. 45, 959-69.

[0005] TSE are the unique infectious diseases that are not transmitted by a nucleic acid-based disease organism. Rather, TSE result from the abnormal conformation of a brain protein, the prion protein (PrP). Prusiner, S. B., 1991, Science 252, 1515-22. The pathologic conformation consists of a 142-amino acid fragment of the PrP that adopts a predominantly β-pleated sheet conformation, which form catalyzes the conversion of other PrP to assume the pathological conformation. Peretz, D., 2001, Protein Science 10, 854-63; Wadsworth, J. D., et al., 1999, Curr Opin Genet Dev 9, 338-45. Though the hypothesis that TSE results from an infectious conformational change in the PrP is not universally accepted outside of the English-speaking world (see, e.g., Lasmezas, C.I., et al., 1997, Science 275, 402-5), it is widely accepted and has been confirmed by examples of inherited protein conformation in yeast. Lindquist, S., 1996, Mol. Psychiatry 1, 376-9; Lindquist, S., 1997, Cell 89, 495-8.

[0006] Whatever uncertainty may remain about the etiology of TSE, the ablation of the host PrP gene results in an animal that is resistant to the disease. Prusiner, S. B., et al., 1993, PNAS 90, 10608-12; Weissmann, C., & Aguzzi, A., 1999, Science 286, 914-15. In addition, dominant disease-resistant alleles of PrP having amino acid substitution can confer resistance to the disease as heterozygotes. Perrier, V. et al., 2002, PNAS 99, 13079-84. While certain biochemical and morphological abnormalities are associated with the PrP-ablated condition, the animals develop normally and appear healthy. Miele, G., et al., 2002, BBRC 291, 372-77; White, A. R., et al., 1999, Am J. Path. 155, 1723-30.

SUMMARY OF THE INVENTION

[0007] The invention provides a method of rendering cattle resistant to BSE by ablation of the bovine PrP gene. Fragments of bovine PrP gene are cloned into bacteria and mutated by known techniques of site directed mutagenesis. The mutated cloned gene is used as a template to generate a short fragment (henceforth “SF”) of between 200-1000 bp, preferably between 400 and 800 bp using conventional oligonucleotide primed polymerase chain reaction amplification. There can be more than one genetic alteration encoded in an SF, but the alterations should be limited in size and extent, so that not more than four consecutive nucleotides of the SF will not be homologous to the target gene. A second alteration without physiological effects may be introduced to facilitate the subsequent isolation of mutant cells that have homologously recombined the SF. The differences between the sequence of the SF and that of the target gene (the “heterologies”) can either be mismatches, insertions or deletions. Ablation is caused by insertion of a frame shift mutation or multiple stop codons.

[0008] The SF is converted to single strand SF (“ssSF”), and then into a strand separated form (“s⁴SF”). The sequence of the SF will preferably be examined to determine self-complementary sequences that will cause extensive self-complementary secondary structure.

[0009] Once formed, the s⁴SF can be introduced into a somatic cell, typically a fibroblast, so as to induce ablation of the PrP gene. Selection of mutated clones is performed by cloning and PCR screening. To facilitate PCR screening, it is preferred that the ablating mutation create a readily observable restriction site, so that mutant clones can be identified without sequencing. Cattle incorporating the mutated PrP gene can be recovered by nuclear transfer to oocytes, using known techniques.

DETAILED DESCRIPTION OF THE INVENTIONS

[0010] Preparation of the s⁴SF and generation of a mutant PrP gene. In one embodiment the invention consists of the use of a short fragment (SF) of single stranded DNA of between 200 and 1000 nt and, more preferably between 400 and 800 nt that is homologous (identical) with a fragment of the bovine PrP gene, except at a limited number of positions, typically fewer than 10, which are designed to introduce ablating mutations into the PrP gene and, optionally generate an additional alteration to facilitate identification of the modified PrP locus by a combination of allele-specific PCR and a secondary detection. The sequence of the bovine PrP gene is found at GENBANK accession No. AJ298878, the sequence of the PrP cDNA can be found as accession AB001468, which are hereby incorporated by reference.

[0011] Construction of the desired, mutated sequence can be most readily accomplished by in vitro site-directed mutagenesis. The techniques involved are well known in the art. Perrin, S., & Gilliland, G., 1990, Nucleic Acid Research 18, 7433; Landt, O., et al., 1990, Gene 96, 125-8; Nassal M., & Rieger, A., 1989, Nucleic Acids Research 18, 3077-8; Hemsley, A., et al., 1989, Nucleic Acids Research 17, 6545-51. Implementation of these techniques require that the target gene or a fragment of the gene that encompasses the sequenced to be modified is available in recombinant clones. Having constructed the appropriate desired sequence, the SF itself can be synthesized by routine polymerase chain reaction (“PCR”). When s⁴SF are to be used, the synthesis employs one 5′-biotinylated primer and one underivitized primer. The strands are separated as described below. The synthesis of 5′-biotinylated primers is well known. Cook, A. F., et al., 1988, Nucleic Acids Research 16, 4077-95; Connolly, B. A., 1988, Nucleic Acids Research 15, 3131-9.

[0012] After the SF is synthesized in a duplex form, i.e., the form in which the fragment is Watson-Crick bound to its complement, a single stranded SF can be prepared. The preparation is most simply accomplished by heat denaturation (heating to 95° C.) followed by rapid cooling to 4° C. This process results in a mixture of strands of both polarity having no or essentially no intermolecular Watson-Crick base pairings. However, continued incubation of the mixture at elevated temperatures can result in the formation of inter-molecular Watson-Crick pairings.

[0013] The separation of the complementary strands can be readily accomplished when one of the two primers used in the PCR synthesis of the SF is biotinylated. Separation of the product can be effected by binding the biotinylated strand to immobilized avidin as follows:

[0014] Double stranded SF (ds-SF) products can be prepared by PCR using two primers, one of which contained a biotin at the 5′ end.

[0015] Single strand preparation:

[0016] Single strands were generated by binding the biotinylated PCR product to avidin-magnetic beads (Dyonex).

[0017] The displaced strand (D-ssSF not containing biotin) was isolated by denaturing the bound dsPCR fragment under high pH (0.5 M NaOH) 1-2 minutes.

[0018] The “displaced strand” (supernatant) was removed from the beads using a magnet or centrifugation, neutralized with acid (27 ul cHCL per 500 :1 0.5 M NaOH) and dialyzed (1000×volume 0.1 M Tris pH 7.0, then 2 Times 1000×volume of water). The displaced strand was then concentrated by ethanol precipitation or spin concentrators.

[0019] The immobilized strand (B-SF) attached to the beads was neutralized with 2 Tris 0.1 M pH 7.0 washes followed by 2 water washes. The immobilized strand was removed from the magnetic beads in water following heat treatment (95° C.).

[0020] Both displaced and immobilized strands individually have activity.

[0021] Typically the displaced strand was more active. Either the coding or non-coding strand may be used to introduce the modification into the targeted gene.

[0022] The s⁴SF can be introduced into a bovine cell, such as a bovine fibroblast, by any method that can be used to introduce duplex DNA into the cell. The preferred method is by microinjection, which allows for individual inoculation of pre-selected, adherent cells in an controlled manner.

[0023] A cell containing the modified target gene can be isolated by cloning and PCR testing of the cloned cells prior to the regeneration of whole animals. Several methods can be employed to identify a clone of cells in which the SF has altered the PrP locus.

[0024] A particular method, which is suitable when the frequency of altered cells is low is termed “coupled detection” (CD) and was described in commonly owned U.S. patent application Ser. No. 10/298,859, filed Nov. 18, 2002, by R. Metz which is hereby incorporated by reference in its entirety. In CD, two alternations, typically between 50 and 100 nucleotides apart, are introduced using a single SF. After a population containing a putatively modified cell is obtained; the population is divided into replicate subgroups. A PCR reaction is performed on genomic DNA from a replicate of each subgroup using a PCR primers that will amplify the target sequence but not the SF. The products of this reaction are diluted and used as template for the second PCR reaction. The second PCR reaction is performed using a PCR primer that preferentially anneals to the sequence of one of the alterations compared to the wild-type sequence and a non-selective second primer. The PCR reaction is designed so that the product includes the site of the second alteration. Suitable selection of annealing temperature results in the preferential amplification of the altered fragment relative to the wild-type. The preferential amplification permits the ready detection of a single copy of the altered genotype in a subgroup of several thousand by detection of the second alteration in the PCR product. A second alteration that creates or deletes a restriction enzyme recognition such that the presence of a mutant locus can be detected by a restriction enzyme digest is particularly preferred because of the ease in detection.

[0025] Using CD, a large population of cells can be readily screened to detect a rare cell that contains the linked alterations. The screening is performed by subdividing the populations into subgroups or about 5,000. The replicates from subgroups that contain a single copy of the rare modified cell are further subdivided and cultured. Successive cycles of subdivision, replica formation and detection can be used to isolate the rare modified cell from the population.

[0026] In a less preferred method, a PCR primer that preferentially anneals to the mutant sequence compared to the wild-type sequence is used to PCR-amplify a genomic fragment from a population of cells under such temperature conditions that only the mutant sequence, if present, yields a product.

[0027] In an alternative embodiment, the alteration in the bovine PrP gene can be made to increase the relative stability of the soluble form of the PrP protein. Mutations that increase the stability have been identified by comparison of the susceptibility of different strains of sheep to scrapie with polymorphism in the ovine PrP gene. Mutations at positions 136, 154 and 171 were found to be protective. Drogenmuller, C., et al., 2001, Vet. Res. 149, 349-52. The same mutations can be introduced into the bovine PrP gene in an alternative embodiment of the invention.

[0028] In yet another embodiment, an alteration of the bovine PrP gene by mutations that confer a dominant disease-resistant phenotype can be introduced into the bovine PrP gene, so that animals would not need to be homozygous for the altered Prp gene to be resistant to the disease.

[0029] Generation of BSE resistant cattle: The generation of domestic animals containing site-specific mutations has been made possible by recent advances in nuclear transplantation from somatic cells into a competent germ-line cell, i.e., oocytes or cells of a blastocyst (blastomers). These techniques are referred to in general as “cloning” or “animal cloning” because they enable the practitioner to make a genetically identical individual from an explanted somatic cell. The techniques are described in detail in U.S. Pat. No. 6,147,276 and No. 6,252,133.

[0030] Scientific publications describing the technology teach that with some species-specific adaptations the techniques have proved successful in sheep, cattle and swine. Schnieke, A. E., et al., 1997, Science 278, 2130-33; Wilmut, I., et al., 1997, Nature 385, 810-3; Polejaeva, I. A., et al., 2000, Nature 407, 29-30. A current review of the field can be found in Kuhholtzer, B., & Prather, R. S., 2000, Proc. Soc. Exp. Med. 224, 240-45.

[0031] It is expected that the originally mutated somatic nucleus will be heterozygous for the PrP mutation. Accordingly, the generation of BSE resistant stock will require interbreeding the founder stock in order to isolate the mutation in homozygous form when the alteration of the PrP gene is designed to prevent its translation. The presence of the modified PrP in offspring of parents carrying a PrP disease-resistant allele can be determined through a DNA-based assay which may include techniques commonly known in the art such as RFLP mapping, SNP detection, southern blots, PCR amplification and direct sequencing. As an alternative to generating an animal homozygous for alterations in the PrP gene, cell lines prepared from embryos derived in the first round of nuclear transfer cloning can be retargeted by SFHR to alter the second PrP allele. The alteration of the second allele can be the same as that of the first allele or alternatively it can be different to aid in the identification of cells having both PrP alleles modified. These mutant cell lines homozygous for altered PrP alleles heterozygous can be used to redone an animal homozygous for the desired PrP gene mutation.

[0032] DNA fragments for SFHR are synthesized by PCR in a two step process using a commercially available vector into which exon 3 of bovine PrP has been inserted. Two types of primers are used. A mutational primer is used to alter the PiP sequence in the vector.

[0033] After the mutation is introduced production primers are used to make the SFHR duplex DNA by PCR using the mutated vector as template.

[0034] Listed below of Forward and Reverse production primers (FP and RP) and mutational primers which are labeled according to the position of the mutation in the amino acid sequence. SFHR PCR Primers LOCATION NUCLEOTIDE FP5 5′ GTGGCCATGTGGAGTGA (SEQ ID NO:1) 281 RP5 5′ CCCAACCTGGTAAAGATTAAG (SEQ ID NO:2) 1061 (rc-cttaatctttaccaggttggg) (SEQ ID NO:3) FP4 5′ CTGTTTATAGCTGATGCCACT (SEQ ID NO:4) 130 RP4 5′ ACGGTTGCCTCCAGGAC (SEQ ID NO:5) 375 (rc-gtcctggaggcaaccgt) (SEQ ID NO:6) RP3 5′ GGCTTACTGGGTTTGTTCC (SEQ ID NO:7) 567 (rc-ggaacaaacccagtaagcc) (SEQ ID NO:8) RP2 5′ GGCCTGTAGTACACTTGGTTG (SEQ ID NO:9) 745 (rc-caaccaagtgtactacaggcc) (SEQ ID NO: 10) Mutagenic primers and SFHR combinations Prp-mutant Primer set Name Sequence SFHR Prp-0-1 W9stop 5′ CACATAGGCAGTTAGATCCTGGTTCTC3′ (SEQ ID NO:11) FP4/Rp2, FP4/RP3, FP4/RP4, FP4/RP5 Prp-0-2 W18stop 5′ TTTGTGGCCATGTAGAGTGACGTGGGC3′ (SEQ ID NO:12) FP4/Rp2, FP4/RP3, FP4/RP4, FP4/RP5 Prp-0-3 C24stop 5′ GACGTGGGCCTCTGAAAGAAGCGACCA3′ (SEQ ID NO:13) FP4/Rp2, FP4/RP3, FP4/RP4, FP4/RP5 Prp-0-4 K3stop 5′ GTCATCATGGTGTAAAGCCACATAGGC3′ (SEQ ID NO:14) FP4/Rp2, FP4/RP3, FP4/RP4, FP4/RP5 Prp-0-d5 V2del 5′ GTCATCATGGT:AAAAGCCACATAGGC3′ (SEQ ID NO:15) FP4/Rp2, FP4/RP3, FP4/RP4, FP4/RP5 Prp-0-d6 H5del 5′ GGTGAAAAGCCA:ATAGGCAGTTGGAT3′ (SEQ ID NO:16) FP4/Rp2, FP4/RP3, FP4/RP4, FP4/RP5 Prp-ARR Q178R 5′ AGGCCAGTGGATCGGTATAGTAACCAG3′ (SEQ ID NO:17) FP4/RP5, FP4/RP3, FP4/RP4, FP4/RP5

[0035] Example: The approach for generating animals resistant to Transmissible Spongiform Encephalopathy (TSE) or Bovine Spongiform Encephalopathy (BSE) will proceed in two parallel tracks. A non-functional PrP allele will be generated in a bovine primary cell line using SFHR (GenEdit) molecules (PrP0-1 and/or PrP0-2, other molecules disrupting the open reading frame may also be attempted such as PrP-0-3, -4, -5, -6 etc). In addition, mutagenic PCR primers will be used to insert a point mutation in a restriction enzyme recognition sequence within 100 nucleotides of any of the above mutations. Mutant cells will be generated which have incorporated the mutant sequence by homologous recombination, and clones of these cells will be screened for the presence of the mutant sequences. Replicate subcultures will be generated and DNA prepared for PCR-amplification. In order to increase our sensitivity and selectivity two rounds of PCR amplification will be performed. The first reaction will use a primer set flanking the PrP targeted region. The products from the first round reaction will be diluted 10,000 fold and used as a template for a an allele-enrichment PCR reaction, where one of the primers is designed to preferentially bind the mutant sequence to selectively enrich for sequences containing the PrP mutations. The allele-enriched PCR product will then be digested with the restriction enzyme whose recognition site was mutated. Uncut PCR products are those that contain the mutant sequences, whereas the presence of two fragments will represent the presence of the wildtype PrP. Subcultures containing the mutant form of PrP will be further subdivided and the process of screening for the mutant PrP will be reiterated until a pure subculture containing modified mutant cells is isolated.

[0036] From the modified cell line animals will be generated using nuclear transfer technology. The reduction of a functional PrP allele may have protective properties based on reduced gene product. A homozygous PrP-0 animal (PrP-0/PrP-0) can be generated by back crossing PrP-0 heterozygotes. In a similar fashion, a BSE resistant allele will be introduced into a breeding stock using SFHR molecules (bPrPAAR and/or other molecules affecting resistant phenotype) to introduce a polymorphism barrier to TSE (BSE). The current evidence for polymorphism barriers to TSE (Scrapie) has been described for scrapie resistant herds of sheep containing Alanine (A), Arginine (R) and Arginine (R) at codons 136, 154, and 171, respectively. The bovine sequence contains the resistance-associated amino acids at positions homologous to 136 and 154 and only the amino acid at 171 need be modified. Homozygote PrPARR/PrPAAR or PrPARR/PrP-0 animals can be generated using standard back crossing and cross breeding strategies with the appropriate homozygote/heterozygote animals.

[0037] A number of mutations that can be generated including several null alleles. Below are examples of three nonsense and two frame shift null mutations. Also given are the base substitutions that generate a bovine PrP-ARR. SFHR molecules will be single stranded coding or non-coding, or denatured double stranded. All null generating SFHR molecules will extend into intron 2 and terminate in the exon 3 (Coding region of PRP). The PrP-ARR alelle will need an SFHR molecule whose sequences are contained in exon 3. bovine ex. #-237 cta gga aac aga gcc agg aat tat ttt aag gtc bovine ex. #-204 aac ttt gtc ctt aga gaa gga aga gtt gtg tta bovine ex. #-171 aca ctt tac cta taa tta ctt tcg tga gat gta bovine ex. #-138 tgg aat gtg aag aat att tat gac cta gac tgt bovine ex. #-105 tta tag ctg atg cca ctg cta tgc agt cat tat bovine ex. #-72 gct aca gac ttt aag tga ttt tta cat ggg cat bovine ex. #-39 atg atg ctg aca ccc tct tta ttt tgc agA TAA bovine ex. #-6 GTC ATC ATG GTG AAA AGC CAC ATA GGC AGT TGG (SEQ ID NOS:18-19)          M   V   K   S   H   I   G   S   W PrP-0-1 #-6 GTC ATC ATG GTG AAA AGC CAC ATA GGC AGT TAG (SEQ ID NOS:20-21)          M   V   K   S   H   I   G   S   * PrP-0-2 #-6 GTC ATC ATG GTG AAA AGC CAC ATA GGC AGT TGG (SEQ ID NOS:22-23)          M   V   K   S   H   I   C   S   W PrP-0-3 #-6 GTC ATC ATG GTG AAA AGC CAC ATA GGC AGT TGG (SEQ ID NOS:24-25)          M   V   K   S   H   I   G   S   W Prp-0-4 #-6 GTC ATC ATG GTG TAA AGC CAC ATA GGC AGT TGG (SEQ ID NO:26)      M    V  * PrP-0-d5 #-6 GTC ATC ATG GT: AAA AGC CAC ATA GGC AGT TGG (SEQ ID NOS:27- 28)      M  V    K   A   T   * PrP-0-d6 #-6 GTC ATC ATG GTG AAA AGC CA: ATA GGC AGT TGG (SEQ ID NOS:29-30)      M   V   K   S   Q   * PrP-ARR #-6 GTC ATC ATG GTG AAA AGC CAC ATA GGC AGT TGG (SEQ ID NOS:31-32)      M   V   K   S   H   I   G   S   W bovine ex. #28 ATC CTG GTT CTC TTT GTG GCC ATG TGG AGT GAC I   L   V   L   F   V   A   M   W   S   D PrP-0-1 #28 ATC CTG GTT CTC TTT GTG GCC ATG TGG AGT GAC PrP-0-2 #28 ATC CTG GTT CTC TTT GTG GCC ATG TAG AGT GAC I   L   V   L   F   V   A   M   * PrP-0-3 #28 ATC CTG GTT CTC TTT GTG GCC ATG TGG AGT GAC I   L   V   L   F   V   A   M   W   S   D Prp-0-4 #28 ATC CTG GTT CTC TTT GTG GCC ATG TGG AGT GAC PrP-0-d5 #28 ATC CTG GTT CTC TTT GTG GCC ATG TGG AGT GAC PrP-0-d6 #28 ATC CTG GTT CTC TTT GTG GCC ATG TGG AGT GAC PrP-ARR #28 ATC CTG GTT CTC TTT GTG GCC ATG TGG AGT GAC I   L   V   L   F   V   A   M   W   S   D bovine ex. #61 GTG GGC CTC TGC AAG AAG CGA CCA AAA CCT GGA V   G   L   C   K   K   R   P   K   P   G PrP-0-1 #61 GTG GGC CTC TGC AAG AAG CGA CCA AAA CCT GGA PrP-0-2 #61 GTG GGC CTC TGC AAG AAG CGA CCA AAA CCT GGA PrP-0-3 #61 GTG GGC CTC TGA AAG AAG CGA CCA AAA CCT GGA V   G   L   * Prp-0-4 #61 GTG GGC CTC TGC AAG AAG CGA CCA AAA CCT GGA PrP-0-d5 #61 GTG GGC CTC TGC AAG AAG CGA CCA AAA CCT GGA PrP-0-d6 #61 GTG GGC CTC TGC AAG AAG CGA CCA AAA CCT GGA PrP-ARR #61 GTG GGC CTC TGC AAG AAG CGA CCA AAA CCT GGA V   G   L   C   K   K   R   P   K   P   G bovine ex. #94 GGA GGA TGG AAC ACT GGG GGG AGC CGA TAC CCA G   G   W   N   T   G   G   S   R   Y   P PrP-0-1 #94 GGA GGA TGG AAC ACT GGG GGG AGC CGA TAC CCA PrP-0-2 #94 GGA GGA TGC AAC ACT GGG GGG AGC CGA TAC CCA PrP-0-3 #94 GGA GGA TGG AAC ACT GGG GGG AGC CGA TAC CCA Prp-0-4 #94 GGA GGA TGG AAC ACT GGG CGG AGC CGA TAC CCA PrP-0-d5 #94 GGA GGA TGG AAC ACT GGG GGG AGC CGA TAC CCA PrP-0-d6 #94 GGA GGA TGG AAC ACT GGG GGG AGC CGA TAC CCA PrP-ARR #94 GGA GGA TGG AAC ACT GGG GGG AGC CGA TAC CCA G   C   W   N   T   C   G   S   R   Y   P bovine ex. #127 GGA CAG GGC AGT CCT GGA GGC AAC CGT TAT CCA G   Q   G   S   P   C   G   N   R   Y   P PrP-0-1 #127 GGA CAG GGC AGT CCT GGA GGC AAC CGT TAT CCA PrP-0-2 #127 GGA CAG GGC AGT CCT GGA GGC AAC CGT TAT CCA PrP-0-3 #127 GGA CAG GGC AGT CCT GGA GGC AAC CGT TAT CCA Prp-0-4 #127 GGA CAG GGC AGT CCT GGA GGC AAC CGT TAT CCA PrP-0-d5 #127 GGA CAG GGC AGT CCT GGA GGC AAC CGT TAT CCA PrP-0-d6 #127 GGA CAG GGC AGT CCT GGA GGC AAC CGT TAT CCA PrP-ARR #127 GGA CAG GGC AGT CCT GGA GGC AAC CGT TAT CCA G   Q   G   S   P   G   G   N   R   Y   P bovine ex. #160 CCT CAG GGA GGG GGT GGC TGG GGT CAG CCC CAT P   Q   G   G   G   G   W   G   Q   P   H PrP-0-1 #160 CCT CAG GGA GGG GGT GGC TGG GGT CAG CCC CAT PrP-0-2 #160 CCT CAG GGA GGG GGT GGC TGG GGT CAG CCC CAT PrP-0-3 #160 CCT CAG GGA GGG GGT GGC TGG GGT CAG CCC CAT Prp-0-4 #160 CCT CAG GGA GGG GGT GGC TGG GGT CAG CCC CAT PrP-0-d5 #160 CCT CAG GGA GGG GGT GGC TGG GGT CAG CCC CAT PrP-0-d6 #160 CCT CAG GGA GGG GGT GGC TGG GGT CAG CCC CAT PrP-ARR #160 CCT CAG GGA GGG GGT GGC TGG GGT CAG CCC CAT P   Q   G   G   G   G   W   G   Q   P   H bovine ex. #193 GGA GGT GGC TGG GGC CAG CCT CAT GGA GGT GGC G   G   G   W   G   Q   P   H   G   G   G PrP-0-1 #193 GGA GGT GGC TGG GGC CAG CCT CAT GGA GGT GGC PrP-0-2 #193 GGA GGT GGC TGG GGC CAG CCT CAT GGA GGT GGC PrP-0-3 #193 GGA GGT GGC TGG GGC CAG CCT CAT GGA GGT GGC Prp-0-4 #193 GGA GGT GGC TGG GGC CAG CCT CAT GGA GGT GGC PrP-0-d5 #193 GGA GGT GGC TGG GGC CAG CCT CAT GGA GGT GGC PrP-0-d6 #193 GGA GGT GGC TGG GGC CAG CCT CAT GGA GGT GGC PrP-ARR #193 GGA GGT GGC TGG GGC CAG CCT CAT GGA GGT GGC G   G   G   W   G   Q   P   H   G   G   G bovine ex. #226 TGG GGC CAG CCT CAT GGA GGT GGC TGG GGT CAG W   G   Q   P   H   G   G   G   W   G   Q PrP-0-1 #226 TGG GGC CAG CCT CAT GGA GGT GGC TGG GGT CAG PrP-0-2 #226 TGG GGC CAG CCT CAT GGA GGT GGC TGG GGT CAG PrP-0-3 #226 TGG GGC CAG CCT CAT GGA GGT GGC TGG GGT CAG Prp-0-4 #226 TGG GGC CAG CCT CAT GGA GGT GGC TGG GGT CAG PrP-0-d5 #226 TGG GGC CAG CCT CAT GGA GGT GGC TGG GGT CAG PrP-0-d6 #226 TGG GGC CAG CCT CAT GGA GGT GGC TGG GGT CAG PrP-ARR #226 TGG GGC CAG CCT CAT GGA GGT GGC TGG GGT CAG   W   C   Q   P   H   G   G   G   W   G   Q bovine ex. #259 CCC CAT GGT GGT GGC GGC GGA CAC CCA CAT GGT P   H   G   G   G   W   G   Q   P   H   G PrP-0-1 #259 CCC CAT GGT GGT GGC TGG GGA CAG CCA CAT GGT PrP-0-2 #259 CCC CAT GGT GGT GGC TGG GGA CAG CCA CAT GGT PrP-0-3 #259 CCC CAT GGT GGT GGC TGG GGA CAG CCA CAT GGT Prp-0-4 #259 CCC CAT GGT GGT GGC TGG GGA CAG CCA CAT GGT PrP-0-d5 #259 CCC CAT GGT GGT GGC TGG GGA CAG CCA CAT GGT PrP-0-d6 #259 CCC CAT GGT GGT GGC TGG GGA CAG CCA CAT GGT PrP-ARR #259 CCC CAT GGT GGT GGC TGG GGA CAG CCA CAT GGT P   H   G   G   G   W   G   Q   P   H   C bovine ex. #292 GGT GGA GGC TGG GGT CAA GGT GGT ACC CAC GGT G   G   G   W   G   Q   G   G   T   H   G PrP-0-1 #292 GGT GGA GGC TGG GGT CAA GGT GGT ACC CAC GGT PrP-0-2 #292 GGT GGA GGC TGG GGT CAA GGT GGT ACC CAC GGT PrP-0-3 #292 GGT GGA GGC TGG GGT CAA GGT GGT ACC CAC GGT Prp-0-4 #292 GGT GGA GGC TGG GGT CAA GGT GGT ACC CAC GGT PrP-0-d5 #292 GGT GGA GGC TGG GGT CAA GGT GGT ACC CAC GGT PrP-0-d6 #292 GGT GGA GGC TGG GGT CAA GGT GGT ACC CAC GGT PrP-ARR #292 GGT GGA GGC TGG GGT CAA GGT GGT ACC CAC GGT G   G   G   W   G   Q   G   G   T   H   G bovine ex. #325 CAA TGG AAC AAA CCC AGT AAG CCA AAA ACC AAC Q   W   N   K   P   S   K   P   K   T   N PrP-0-1 #325 CAA TGG AAC AAA CCC AGT AAG CCA AAA ACC AAC PrP-0-2 #325 CAA TGG AAC AAA CCC AGT AAG CCA AAA ACC AAC PrP-0-3 #325 CAA TGG AAC AAA CCC AGT AAG CCA AAA ACC AAC Prp-0-4 #325 CAA TGG AAC AAA CCC AGT AAG CCA AAA ACC AAC PrP-0-d5 #325 CAA TGG AAC AAA CCC AGT AAG CCA AAA ACC AAC PrP-0-d6 #325 CAA TGG AAC AAA CCC AGT AAG CCA AAA ACC AAC PrP-ARR #325 CAA TGG AAC AAA CCC AGT AAG CCA AAA ACC AAC Q   W   N   K   P   S   K   P   K   T   N bovine ex. #358 ATG AAG CAT GTG GCA GGA GCT GCT GCA GCT GGA M   K   H   V   A   G   A   A   A   A   G PrP-0-1 #358 ATG AAG CAT GTG GCA GGA GCT GCT GCA GCT GGA PrP-0-2 #358 ATG AAG CAT GTG GCA GGA GCT GCT GCA GCT GGA PrP-0-3 #358 ATG AAG CAT GTG GCA GGA GCT GCT GCA GCT GGA Prp-0-4 #358 ATG AAG CAT GTG GCA GGA GCT GCT GCA GCT GGA PrP-0-d5 #358 ATG AAG CAT GTG GCA GGA GCT GCT GCA GCT GGA PrP-O-d6 #358 ATG AAG CAT GTG GCA GGA GCT GCT GCA GCT GGA PrP-ARR #358 ATG AAG CAT GTG GCA GGA GCT GCT GCA GCT GGA M   K   H   V   A   G   A   A   A   A   G bovine ex. #391 GCA GTG GTA GGG GGC CTT GGT GGC TAC ATG CTG A   V   V   G   G   L   G   G   Y   M   L PrP-0-1 #391 GCA GTG GTA GGG GGC CTT GGT GGC TAC ATG CTG PrP-0-2 #391 GCA GTG GTA GGG GGC CTT GGT GGC TAC ATG CTG PrP-0-3 #391 GCA GTG GTA GGG GGC CTT GGT GGC TAC ATG CTG Prp-0-4 #391 GCA GTG GTA GGG GGC CTT GGT GGC TAC ATG CTG PrP-0-d5 #391 GCA GTG GTA GGG GGC CTT GGT GGC TAC ATG CTG PrP-0-d6 #391 GCA GTG GTA GGG GGC CTT GGT GGC TAC ATG CTG PrP-ARR #391 GCA GTG GTA GGG GGC CTT GGT GGC TAC ATG CTG A   V   V   G   G   L   G   G   Y   M   L bovine ex. #424 GGA AGT GCC ATG AGC AGG CCT CTT ATA CAT TTT G   S   A   M   S   R   P   L   I   H   F PrP-0-1 #424 GGA AGT GCC ATG AGC AGG CCT CTT ATA CAT TTT PrP-0-2 #424 GGA AGT GCC ATG AGC AGG CCT CTT ATA CAT TTT PrP-0-3 #424 GGA AGT GCC ATG AGC AGG CCT CTT ATA CAT TTT Prp-0-4 #424 GGA AGT GCC ATG AGC AGG CCT CTT ATA CAT TTT PrP-0-d5 #424 GGA AGT GCC ATG AGC AGG CCT CTT ATA CAT TTT PrP-0-d6 #424 GGA AGT GCC ATG AGC AGG CCT CTT ATA CAT TTT PrP-ARR #424 GGA AGT GCC ATG AGC AGG CCT CTT ATA CAT TTT   G   S   A   M   S   R   P   L   I   H   F bovine ex. #457 GGC AGT GAC TAT GAG GAC CGT TAC TAT CGT GAA G   S   D   Y   E   D   R   Y   Y   R   E PrP-0-1 #457 GGC AGT GAC TAT GAG GAC CGT TAC TAT CGT GAA PrP-0-2 #457 GGC AGT GAC TAT GAG GAC CGT TAC TAT CGT GAA PrP-0-3 #457 GGC AGT GAC TAT GAG GAC CGT TAC TAT CGT GAA Prp-0-4 #457 GGC AGT GAC TAT GAG GAC CGT TAC TAT CGT GAA PrP-0-d5 #457 GGC AGT GAC TAT GAG GAC CGT TAC TAT CGT GAA PrP-0-d6 #457 GGC AGT GAC TAT GAG GAC CGT TAC TAT CGT GAA PrP-ARR #457 GGC AGT GAC TAT GAG GAC CGT TAG TAT CGT GAA   G   S   D   Y   E   D   R   Y   Y   R   E bovine ex. #490 AAC ATG CAC CGT TAC CCC AAC CAA GTG TAC TAC N   M   H   R   Y   P   N   Q   V   Y   Y PrP-0-1 #490 AAC ATG CAC CGT TAC CCC AAC CAA GTG TAC TAC PrP-0-2 #490 AAC ATG CAC CGT TAC CCC AAC CAA GTG TAC TAC PrP-0-3 #490 AAC ATG CAC CGT TAC CCC AAC CAA GTG TAC TAC Prp-0-4 #490 AAC ATG CAC CGT TAC CCC AAC CAA GTG TAC TAC PrP-0-d5 #490 AAC ATG CAC CGT TAC CCC AAC CAA GTG TAC TAC PrP-0-d6 #490 AAC ATG CAC CGT TAC CCC AAC CAA GTG TAC TAC PrP-ARR #490 AAC ATG CAC CGT TAC CCC AAC CAA GTG TAC TAC N   M   H   R   Y   P   N   Q   V   Y   Y bovine ex. #523 AGG CCA GTG GAT CAG TAT AGT AAC CAG AAC AAC R   P   V   D   Q   Y   S   N   Q   N   N PrP-0-1 #523 AGG CCA GTG GAT CAG TAT AGT AAC CAG AAC AAC PrP-0-2 #523 AGG CCA GTG GAT CAG TAT AGT AAC CAG AAC AAC PrP-0-3 #523 AGG CCA GTG GAT CAG TAT AGT AAC CAG AAC AAC Prp-0-4 #523 AGG CCA GTG GAT CAG TAT AGT AAC CAG AAC AAC PrP-0-d5 #523 AGG CCA GTG GAT CAG TAT AGT AAC CAG AAC AAC PrP-0-d6 #523 AGG CCA GTG GAT CAG TAT AGT AAC CAG AAC AAC PrP-ARR #523 AGG CCA GTG GAT CGG TAT AGT AAC CAG AAC AAC R   P   V   D   R   Y   S   N   Q   N   N                  * AA171 bovine ex. #556 TTT GTG CAT GAC TGT GTC AAC ATC ACA GTC AAG F   V   H   D   C   V   N   I   T   V   K PrP-0-1 #556 TTT GTG CAT GAC TGT GTC AAC ATC ACA GTC AAG PrP-0-2 #556 TTT GTG CAT GAC TGT GTC AAC ATC ACA GTC AAG PrP-0-3 #556 TTT GTG CAT GAC TGT GTC AAC ATC ACA GTC AAG Prp-0-4 #556 TTT GTG CAT GAC TGT GTC AAC ATC ACA GTC AAG PrP-0-d5 #556 TTT GTG CAT GAC TGT GTC AAC ATC ACA GTC AAG PrP-0-d6 #556 TTT GTG CAT GAC TGT GTC AAC ATC ACA GTC AAG PrP-ARR #556 TTT GTG CAT GAC TGT GTC AAC ATC ACA GTC AAG   F   V   H   D   C   V   N   I   T   V   K bovine ex. #589 GAA CAC ACA GTC ACC ACC ACC ACC AAG GGG GAG   E   H   T   V   T   T   T   T   K   G   E PrP-0-1 #589 GAA CAC ACA GTC ACC ACC ACC ACC AAG GGG GAG PrP-0-2 #589 GAA CAC ACA GTC ACC ACC ACC ACC AAG GGG GAG PrP-0-3 #589 GAA CAC ACA GTC ACC ACC ACC ACC AAG GGG GAG Prp-0-4 #589 GAA CAC ACA GTC ACC ACC ACC ACC AAG GGG GAG PrP-0-d5 #589 GAA CAC ACA GTC ACC ACC ACC ACC AAG GGG GAG PrP-0-d6 #589 GAA CAC ACA GTC ACC ACC ACC ACC AAG GGG GAG PrP-ARR #589 GAA CAC ACA GTC ACC ACC ACC ACC AAG GGG GAG   E   H   T   V   T   T   T   T   K   G   E bovine ex. #622 AAC TTC ACC GAA ACT GAC ATC AAG ATG ATG GAG N   F   T   E   T   D   I   K   M   M   H PrP-0-1 #622 AAC TTC ACC GAA ACT GAC ATC AAG ATG ATG GAG PrP-O-2 #622 AAC TTC ACC GAA ACT GAC ATC AAG ATG ATG GAG PrP-0-3 #622 AAC TTC ACC GAA ACT GAC ATC AAG ATG ATG GAG Prp-0-4 #622 AAC TTC ACC GAA ACT GAC ATC AAG ATG ATG GAG PrP-0-d5 #622 AAC TTC ACC GAA ACT GAC ATC AAG ATG ATG GAG PrP-0-d6 #622 AAC TTC ACC GAA ACT GAC ATC AAG ATG ATG GAG PrP-ARR #622 AAC TTC ACC GAA ACT GAC ATC AAG ATG ATG GAG N   F   T   E   T   D   I   K   M   M   H bovine ex. #655 CGA GTG GTG GAG CAA ATG TGC ATT ACC CAG TAC PrP-0-1 #655 CGA GTG GTG GAG CAA ATG TGC ATT ACC CAG TAC PrP-0-2 #655 CGA GTG GTG GAG CAA ATG TGC ATT ACC CAG TAC PrP-0-3 #655 CGA GTG GTG GAG CAA ATG TGC ATT ACC CAG TAC Prp-0-4 #655 CGA GTG GTG GAG CAA ATG TGC ATT ACC CAG TAC PrP-0-d5 #655 CGA GTG GTG GAG CAA ATG TGC ATT ACC CAG TAC PrP-0-d6 #655 CGA GTG GTG GAG CAA ATG TGC ATT ACC CAG TAC PrP-ARR #655 CGA GTG GTG GAG CAA ATG TGC ATT ACC CAG TAC R   V   V   E   Q   M   C   I   T   Q   Y bovine ex. #688 CAG AGA GAA TCC CAG GCT TAT TAC CAA CGA GGG Q   R   E   S   Q   A   Y   Y   Q   R   G PrP-0-1 #688 CAG AGA GAA TCC CAG GCT TAT TAC CAA CGA GGG PrP-0-2 #688 CAG AGA GAA TCC CAG GCT TAT TAC CAA CGA GGG PrP-0-3 #688 CAG AGA GAA TCC CAG GCT TAT TAC CAA CGA GGG Prp-0-4 #688 CAG AGA GAA TCC CAG GCT TAT TAC CAA CGA GGG PrP-0-d5 #688 CAG AGA GAA TCC CAG GCT TAT TAC CAA CGA GGG PrP-0-d6 #688 CAG AGA GAA TCC CAG GCT TAT TAC CAA CGA GGG PrP-ARR #688 CAG AGA GAA TCC CAG GCT TAT TAC CAA CGA GGG   Q   R   E   S   Q   A   Y   Y   Q   R   G bovine ex. #721 GCA AGT GTG ATC CTC TTC TCT TCC CCT CCT GTG A   S   V   I   L   F   S   S   P   P   V PrP-0-1 #721 GCA AGT GTG ATC CTC TTC TCT TCC CCT CCT GTG PrP-0-2 #721 GCA AGT GTG ATC CTC TTC TCT TCC CCT CCT GTG PrP-0-3 #721 GCA AGT GTG ATC CTC TTC TCT TCC CCT CCT GTG Prp-0-4 #721 GCA AGT GTG ATC CTC TTC TCT TCC CCT CCT GTG PrP-0-d5 #721 GCA AGT GTG ATC CTC TTC TCT TCC CCT CCT GTG PrP-G-d6 #721 GCA AGT GTG ATC CTC TTC TCT TCC CCT CCT GTG PrP-ARR #721 GCA AGT GTG ATC CTC TTC TCT TCC CCT CCT GTG A   S   V   I   L   F   S   S   P   P   V bovine ex. #754 ATC CTC CTC ATC TCT TTC CTC ATT TTT CTC ATA   I   L   L   I   S   F   L   I   F   L   I PrP-0-1 #754 ATC CTC CTC ATC TCT TTC CTC ATT TTT CTC ATA I   L   L   I   S   F   L   I   F   L   I PrP-0-2 #754 ATC CTC CTC ATC TCT TTC CTC ATT TTT CTC ATA PrP-0-3 #754 ATC CTC CTC ATC TCT TTC CTC ATT TTT CTC ATA Prp-0-4 #754 ATC CTC CTC ATC TCT TTC CTC ATT TTT CTC ATA PrP-0-d5 #754 ATC CTC CTC ATC TCT TTC CTC ATT TTT CTC ATA PrP-0-d6 #754 ATC CTC CTC ATC TCT TTC CTC ATT TTT CTC ATA PrP-ARR #754 ATC CTC CTC ATC TCT TTC CTC ATT TTT CTC ATA I   L   L   I   S   F   L   I   F   L   I bovine ex. #787 GTA GGA TAG GGG CAA CCT TCC TGT TTT CAT TAT   V   G  * PrP-0-1 #787 GTA GGA TAG GGG CAA CCT TCC TGT TTT CAT TAT PrP-0-2 #787 GTA GGA TAG GGG CAA CCT TCC TGT TTT CAT TAT PrP-0-3 #787 GTA GGA TAG GGG CAA CCT TCC TGT TTT CAT TAT Prp-0-4 #787 GTA GGA TAG GGG CAA CCT TCC TGT TTT CAT TAT PrP-0-d5 #787 GTA GGA TAG GGG CAA CCT TCC TGT TTT CAT TAT PrP-0-d6 #787 GTA GGA TAG GGG CAA CCT TCC TGT TTT CAT TAT PrP-ARR #787 GTA GGA TAG GGG CAA CCT TCC TGT TTT CAT TAT   V   G  * bovine ex. #820 CTT CTT AAT CTT TAC CAG GTT GGG GGA GGG AGT PrP-0-1 #820 CTT CTT AAT CTT TAC CAG GTT GGG GGA GGG AGT PrP-0-2 #820 CTT CTT AAT CTT TAC CAG GTT GGG GGA GGG AGT PrP-0-3 #820 CTT CTT AAT CTT TAC CAG GTT GGG GGA GGG AGT prp-0-4 #820 CTT CTT AAT CTT TAC CAG GTT GGG GGA GGG AGT PrP-0-d5 #820 CTT CTT AAT CTT TAC CAG GTT GGG GGA GGG AGT PrP-0-d6 #820 CTT CTT AAT CTT TAC CAG GTT GGG GGA GGC AGT PrP-ARR #820 CTT CTT AAT CTT TAC CAG GTT GGG GGA GGG AGT

[0038]

1 32 1 17 DNA Artificial Sequence forward primer 1 gtggccatgt ggagtga 17 2 21 DNA Artificial Sequence reverse primer 2 cccaacctgg taaagattaa g 21 3 21 DNA Artificial Sequence reverse complement of SEQ ID NO2 3 cttaatcttt accaggttgg g 21 4 21 DNA Artificial Sequence forward primer 4 ctgtttatag ctgatgccac t 21 5 17 DNA Artificial Sequence reverse primer 5 acggttgcct ccaggac 17 6 17 DNA Artificial Sequence reverse complement of SEQ ID NO5 6 gtcctggagg caaccgt 17 7 19 DNA Artificial Sequence reverse primer 7 ggcttactgg gtttgttcc 19 8 19 DNA Artificial Sequence reverse complement of SEQ ID NO7 8 ggaacaaacc cagtaagcc 19 9 21 DNA Artificial Sequence reverse primer 9 ggcctgtagt acacttggtt g 21 10 21 DNA Artificial Sequence reverse complement of SEQ ID NO9 10 caaccaagtg tactacaggc c 21 11 27 DNA Artificial Sequence W9stop primer 11 cacataggca gttagatcct ggttctc 27 12 27 DNA Artificial Sequence W18stop primer 12 tttgtggcca tgtagagtga cgtgggc 27 13 27 DNA Artificial Sequence C24stop primer 13 gacgtgggcc tctgaaagaa gcgacca 27 14 27 DNA Artificial Sequence K3stop 14 gtcatcatgg tgtaaagcca cataggc 27 15 26 DNA Artificial Sequence V2del primer 15 gtcatcatgg taaaagccac ataggc 26 16 26 DNA Artificial Sequence H5del primer 16 ggtgaaaagc caataggcag ttggat 26 17 27 DNA Artificial Sequence Q178R primer 17 aggccagtgg atcggtatag taaccag 27 18 1089 DNA Bos taurus CDS (238)..(1032) 18 ctaggaaaca gagccaggaa ttattttaag gtcaactttg tccttagaga aggaagagtt 60 gtgttaacac tttacctata attactttcg tgagatgtat ggaatgtgaa gaatatttat 120 gacctagact gtttatagct gatgccactg ctatgcagtc attatgctac agactttaag 180 tgatttttac atgggcatat gatgctgaca ccctctttat tttgcagata agtcatc 237 atg gtg aaa agc cac ata ggc agt tgg atc ctg gtt ctc ttt gtg gcc 285 Met Val Lys Ser His Ile Gly Ser Trp Ile Leu Val Leu Phe Val Ala 1 5 10 15 atg tgg agt gac gtg ggc ctc tgc aag aag cga cca aaa cct gga gga 333 Met Trp Ser Asp Val Gly Leu Cys Lys Lys Arg Pro Lys Pro Gly Gly 20 25 30 gga tgg aac act ggg ggg agc cga tac cca gga cag ggc agt cct gga 381 Gly Trp Asn Thr Gly Gly Ser Arg Tyr Pro Gly Gln Gly Ser Pro Gly 35 40 45 ggc aac cgt tat cca cct cag gga ggg ggt ggc tgg ggt cag ccc cat 429 Gly Asn Arg Tyr Pro Pro Gln Gly Gly Gly Gly Trp Gly Gln Pro His 50 55 60 gga ggt ggc tgg ggc cag cct cat gga ggt ggc tgg ggc cag cct cat 477 Gly Gly Gly Trp Gly Gln Pro His Gly Gly Gly Trp Gly Gln Pro His 65 70 75 80 gga ggt ggc tgg ggt cag ccc cat ggt ggt ggc tgg gga cag cca cat 525 Gly Gly Gly Trp Gly Gln Pro His Gly Gly Gly Trp Gly Gln Pro His 85 90 95 ggt ggt gga ggc tgg ggt caa ggt ggt acc cac ggt caa tgg aac aaa 573 Gly Gly Gly Gly Trp Gly Gln Gly Gly Thr His Gly Gln Trp Asn Lys 100 105 110 ccc agt aag cca aaa acc aac atg aag cat gtg gca gga gct gct gca 621 Pro Ser Lys Pro Lys Thr Asn Met Lys His Val Ala Gly Ala Ala Ala 115 120 125 gct gga gca gtg gta ggg ggc ctt ggt ggc tac atg ctg gga agt gcc 669 Ala Gly Ala Val Val Gly Gly Leu Gly Gly Tyr Met Leu Gly Ser Ala 130 135 140 atg agc agg cct ctt ata cat ttt ggc agt gac tat gag gac cgt tac 717 Met Ser Arg Pro Leu Ile His Phe Gly Ser Asp Tyr Glu Asp Arg Tyr 145 150 155 160 tat cgt gaa aac atg cac cgt tac ccc aac caa gtg tac tac agg cca 765 Tyr Arg Glu Asn Met His Arg Tyr Pro Asn Gln Val Tyr Tyr Arg Pro 165 170 175 gtg gat cag tat agt aac cag aac aac ttt gtg cat gac tgt gtc aat 813 Val Asp Gln Tyr Ser Asn Gln Asn Asn Phe Val His Asp Cys Val Asn 180 185 190 atc aca gtc aag gaa cac aca gtc acc acc acc acc aag ggg gag aac 861 Ile Thr Val Lys Glu His Thr Val Thr Thr Thr Thr Lys Gly Glu Asn 195 200 205 ttc acc gaa act gac atc aag atg atg aag cga gtg gtg gag caa atg 909 Phe Thr Glu Thr Asp Ile Lys Met Met Lys Arg Val Val Glu Gln Met 210 215 220 tgc att acc cag tac cag aga gaa tcc cag gct tat tac caa cga ggg 957 Cys Ile Thr Gln Tyr Gln Arg Glu Ser Gln Ala Tyr Tyr Gln Arg Gly 225 230 235 240 gca agt gtg atc ctc ttc tct tcc cct cct gtg atc ctc ctc atc tct 1005 Ala Ser Val Ile Leu Phe Ser Ser Pro Pro Val Ile Leu Leu Ile Ser 245 250 255 ttc ctc att ttt ctc ata gta gga tag gggcaacctt cctgttttca 1052 Phe Leu Ile Phe Leu Ile Val Gly 260 ttatcttctt aatctttacc aggttggggg agggagt 1089 19 264 PRT Bos taurus 19 Met Val Lys Ser His Ile Gly Ser Trp Ile Leu Val Leu Phe Val Ala 1 5 10 15 Met Trp Ser Asp Val Gly Leu Cys Lys Lys Arg Pro Lys Pro Gly Gly 20 25 30 Gly Trp Asn Thr Gly Gly Ser Arg Tyr Pro Gly Gln Gly Ser Pro Gly 35 40 45 Gly Asn Arg Tyr Pro Pro Gln Gly Gly Gly Gly Trp Gly Gln Pro His 50 55 60 Gly Gly Gly Trp Gly Gln Pro His Gly Gly Gly Trp Gly Gln Pro His 65 70 75 80 Gly Gly Gly Trp Gly Gln Pro His Gly Gly Gly Trp Gly Gln Pro His 85 90 95 Gly Gly Gly Gly Trp Gly Gln Gly Gly Thr His Gly Gln Trp Asn Lys 100 105 110 Pro Ser Lys Pro Lys Thr Asn Met Lys His Val Ala Gly Ala Ala Ala 115 120 125 Ala Gly Ala Val Val Gly Gly Leu Gly Gly Tyr Met Leu Gly Ser Ala 130 135 140 Met Ser Arg Pro Leu Ile His Phe Gly Ser Asp Tyr Glu Asp Arg Tyr 145 150 155 160 Tyr Arg Glu Asn Met His Arg Tyr Pro Asn Gln Val Tyr Tyr Arg Pro 165 170 175 Val Asp Gln Tyr Ser Asn Gln Asn Asn Phe Val His Asp Cys Val Asn 180 185 190 Ile Thr Val Lys Glu His Thr Val Thr Thr Thr Thr Lys Gly Glu Asn 195 200 205 Phe Thr Glu Thr Asp Ile Lys Met Met Lys Arg Val Val Glu Gln Met 210 215 220 Cys Ile Thr Gln Tyr Gln Arg Glu Ser Gln Ala Tyr Tyr Gln Arg Gly 225 230 235 240 Ala Ser Val Ile Leu Phe Ser Ser Pro Pro Val Ile Leu Leu Ile Ser 245 250 255 Phe Leu Ile Phe Leu Ile Val Gly 260 20 858 DNA Bos taurus CDS (7)..(33) 20 gtcatc atg gtg aaa agc cac ata ggc agt tag atcctggttc tctttgtggc 53 Met Val Lys Ser His Ile Gly Ser 1 5 catgtggagt gacgtgggcc tctgcaagaa gcgaccaaaa cctggaggag gatggaacac 113 tggggggagc cgatacccag gacagggcag tcctggaggc aaccgttatc cacctcaggg 173 agggggtggc tggggtcagc cccatggagg tggctggggc cagcctcatg gaggtggctg 233 gggccagcct catggaggtg gctggggtca gccccatggt ggtggctggg gacagccaca 293 tggtggtgga ggctggggtc aaggtggtac ccacggtcaa tggaacaaac ccagtaagcc 353 aaaaaccaac atgaagcatg tggcaggagc tgctgcagct ggagcagtgg tagggggcct 413 tggtggctac atgctgggaa gtgccatgag caggcctctt atacattttg gcagtgacta 473 tgaggaccgt tactatcgtg aaaacatgca ccgttacccc aaccaagtgt actacaggcc 533 agtggatcag tatagtaacc agaacaactt tgtgcatgac tgtgtcaata tcacagtcaa 593 ggaacacaca gtcaccacca ccaccaaggg ggagaacttc accgaaactg acatcaagat 653 gatgaagcga gtggtggagc aaatgtgcat tacccagtac cagagagaat cccaggctta 713 ttaccaacga ggggcaagtg tgatcctctt ctcttcccct cctgtgatcc tcctcatctc 773 tttcctcatt tttctcatag taggataggg gcaaccttcc tgttttcatt atcttcttaa 833 tctttaccag gttgggggag ggagt 858 21 8 PRT Bos taurus 21 Met Val Lys Ser His Ile Gly Ser 1 5 22 858 DNA Bos taurus CDS (7)..(60) 22 gtcatc atg gtg aaa agc cac ata ggc agt tgg atc ctg gtt ctc ttt 48 Met Val Lys Ser His Ile Gly Ser Trp Ile Leu Val Leu Phe 1 5 10 gtg gcc atg tag agtgacgtgg gcctctgcaa gaagcgacca aaacctggag 100 Val Ala Met 15 gaggatggaa cactgggggg agccgatacc caggacaggg cagtcctgga ggcaaccgtt 160 atccacctca gggagggggt ggctggggtc agccccatgg aggtggctgg ggccagcctc 220 atggaggtgg ctggggccag cctcatggag gtggctgggg tcagccccat ggtggtggct 280 ggggacagcc acatggtggt ggaggctggg gtcaaggtgg tacccacggt caatggaaca 340 aacccagtaa gccaaaaacc aacatgaagc atgtggcagg agctgctgca gctggagcag 400 tggtaggggg ccttggtggc tacatgctgg gaagtgccat gagcaggcct cttatacatt 460 ttggcagtga ctatgaggac cgttactatc gtgaaaacat gcaccgttac cccaaccaag 520 tgtactacag gccagtggat cagtatagta accagaacaa ctttgtgcat gactgtgtca 580 atatcacagt caaggaacac acagtcacca ccaccaccaa gggggagaac ttcaccgaaa 640 ctgacatcaa gatgatgaag cgagtggtgg agcaaatgtg cattacccag taccagagag 700 aatcccaggc ttattaccaa cgaggggcaa gtgtgatcct cttctcttcc cctcctgtga 760 tcctcctcat ctctttcctc atttttctca tagtaggata ggggcaacct tcctgttttc 820 attatcttct taatctttac caggttgggg gagggagt 858 23 17 PRT Bos taurus 23 Met Val Lys Ser His Ile Gly Ser Trp Ile Leu Val Leu Phe Val Ala 1 5 10 15 Met 24 858 DNA Bos taurus CDS (7)..(78) 24 gtcatc atg gtg aaa agc cac ata ggc agt tgg atc ctg gtt ctc ttt 48 Met Val Lys Ser His Ile Gly Ser Trp Ile Leu Val Leu Phe 1 5 10 gtg gcc atg tgg agt gac gtg ggc ctc tga aagaagcgac caaaacctgg 98 Val Ala Met Trp Ser Asp Val Gly Leu 15 20 aggaggatgg aacactgggg ggagccgata cccaggacag ggcagtcctg gaggcaaccg 158 ttatccacct cagggagggg gtggctgggg tcagccccat ggaggtggct ggggccagcc 218 tcatggaggt ggctggggcc agcctcatgg aggtggctgg ggtcagcccc atggtggtgg 278 ctggggacag ccacatggtg gtggaggctg gggtcaaggt ggtacccacg gtcaatggaa 338 caaacccagt aagccaaaaa ccaacatgaa gcatgtggca ggagctgctg cagctggagc 398 agtggtaggg ggccttggtg gctacatgct gggaagtgcc atgagcaggc ctcttataca 458 ttttggcagt gactatgagg accgttacta tcgtgaaaac atgcaccgtt accccaacca 518 agtgtactac aggccagtgg atcagtatag taaccagaac aactttgtgc atgactgtgt 578 caatatcaca gtcaaggaac acacagtcac caccaccacc aagggggaga acttcaccga 638 aactgacatc aagatgatga agcgagtggt ggagcaaatg tgcattaccc agtaccagag 698 agaatcccag gcttattacc aacgaggggc aagtgtgatc ctcttctctt cccctcctgt 758 gatcctcctc atctctttcc tcatttttct catagtagga taggggcaac cttcctgttt 818 tcattatctt cttaatcttt accaggttgg gggagggagt 858 25 23 PRT Bos taurus 25 Met Val Lys Ser His Ile Gly Ser Trp Ile Leu Val Leu Phe Val Ala 1 5 10 15 Met Trp Ser Asp Val Gly Leu 20 26 858 DNA Bos taurus CDS (7)..(15) 26 gtcatc atg gtg taa agccacatag gcagttggat cctggttctc tttgtggcca 55 Met Val 1 tgtggagtga cgtgggcctc tgcaagaagc gaccaaaacc tggaggagga tggaacactg 115 gggggagccg atacccagga cagggcagtc ctggaggcaa ccgttatcca cctcagggag 175 ggggtggctg gggtcagccc catggaggtg gctggggcca gcctcatgga ggtggctggg 235 gccagcctca tggaggtggc tggggtcagc cccatggtgg tggctgggga cagccacatg 295 gtggtggagg ctggggtcaa ggtggtaccc acggtcaatg gaacaaaccc agtaagccaa 355 aaaccaacat gaagcatgtg gcaggagctg ctgcagctgg agcagtggta gggggccttg 415 gtggctacat gctgggaagt gccatgagca ggcctcttat acattttggc agtgactatg 475 aggaccgtta ctatcgtgaa aacatgcacc gttaccccaa ccaagtgtac tacaggccag 535 tggatcagta tagtaaccag aacaactttg tgcatgactg tgtcaatatc acagtcaagg 595 aacacacagt caccaccacc accaaggggg agaacttcac cgaaactgac atcaagatga 655 tgaagcgagt ggtggagcaa atgtgcatta cccagtacca gagagaatcc caggcttatt 715 accaacgagg ggcaagtgtg atcctcttct cttcccctcc tgtgatcctc ctcatctctt 775 tcctcatttt tctcatagta ggataggggc aaccttcctg ttttcattat cttcttaatc 835 tttaccaggt tgggggaggg agt 858 27 857 DNA Bos taurus CDS (7)..(24) 27 gtcatc atg gta aaa gcc aca tag gcagttggat cctggttctc tttgtggcca 54 Met Val Lys Ala Thr 1 5 tgtggagtga cgtgggcctc tgcaagaagc gaccaaaacc tggaggagga tggaacactg 114 gggggagccg atacccagga cagggcagtc ctggaggcaa ccgttatcca cctcagggag 174 ggggtggctg gggtcagccc catggaggtg gctggggcca gcctcatgga ggtggctggg 234 gccagcctca tggaggtggc tggggtcagc cccatggtgg tggctgggga cagccacatg 294 gtggtggagg ctggggtcaa ggtggtaccc acggtcaatg gaacaaaccc agtaagccaa 354 aaaccaacat gaagcatgtg gcaggagctg ctgcagctgg agcagtggta gggggccttg 414 gtggctacat gctgggaagt gccatgagca ggcctcttat acattttggc agtgactatg 474 aggaccgtta ctatcgtgaa aacatgcacc gttaccccaa ccaagtgtac tacaggccag 534 tggatcagta tagtaaccag aacaactttg tgcatgactg tgtcaatatc acagtcaagg 594 aacacacagt caccaccacc accaaggggg agaacttcac cgaaactgac atcaagatga 654 tgaagcgagt ggtggagcaa atgtgcatta cccagtacca gagagaatcc caggcttatt 714 accaacgagg ggcaagtgtg atcctcttct cttcccctcc tgtgatcctc ctcatctctt 774 tcctcatttt tctcatagta ggataggggc aaccttcctg ttttcattat cttcttaatc 834 tttaccaggt tgggggaggg agt 857 28 5 PRT Bos taurus 28 Met Val Lys Ala Thr 1 5 29 857 DNA Bos taurus CDS (7)..(24) 29 gtcatc atg gtg aaa agc caa tag gcagttggat cctggttctc tttgtggcca 54 Met Val Lys Ser Gln 1 5 tgtggagtga cgtgggcctc tgcaagaagc gaccaaaacc tggaggagga tggaacactg 114 gggggagccg atacccagga cagggcagtc ctggaggcaa ccgttatcca cctcagggag 174 ggggtggctg gggtcagccc catggaggtg gctggggcca gcctcatgga ggtggctggg 234 gccagcctca tggaggtggc tggggtcagc cccatggtgg tggctgggga cagccacatg 294 gtggtggagg ctggggtcaa ggtggtaccc acggtcaatg gaacaaaccc agtaagccaa 354 aaaccaacat gaagcatgtg gcaggagctg ctgcagctgg agcagtggta gggggccttg 414 gtggctacat gctgggaagt gccatgagca ggcctcttat acattttggc agtgactatg 474 aggaccgtta ctatcgtgaa aacatgcacc gttaccccaa ccaagtgtac tacaggccag 534 tggatcagta tagtaaccag aacaactttg tgcatgactg tgtcaatatc acagtcaagg 594 aacacacagt caccaccacc accaaggggg agaacttcac cgaaactgac atcaagatga 654 tgaagcgagt ggtggagcaa atgtgcatta cccagtacca gagagaatcc caggcttatt 714 accaacgagg ggcaagtgtg atcctcttct cttcccctcc tgtgatcctc ctcatctctt 774 tcctcatttt tctcatagta ggataggggc aaccttcctg ttttcattat cttcttaatc 834 tttaccaggt tgggggaggg agt 857 30 5 PRT Bos taurus 30 Met Val Lys Ser Gln 1 5 31 858 DNA Bos taurus CDS (7)..(801) 31 gtcatc atg gtg aaa agc cac ata ggc agt tgg atc ctg gtt ctc ttt 48 Met Val Lys Ser His Ile Gly Ser Trp Ile Leu Val Leu Phe 1 5 10 gtg gcc atg tgg agt gac gtg ggc ctc tgc aag aag cga cca aaa cct 96 Val Ala Met Trp Ser Asp Val Gly Leu Cys Lys Lys Arg Pro Lys Pro 15 20 25 30 gga gga gga tgg aac act ggg ggg agc cga tac cca gga cag ggc agt 144 Gly Gly Gly Trp Asn Thr Gly Gly Ser Arg Tyr Pro Gly Gln Gly Ser 35 40 45 cct gga ggc aac cgt tat cca cct cag gga ggg ggt ggc tgg ggt cag 192 Pro Gly Gly Asn Arg Tyr Pro Pro Gln Gly Gly Gly Gly Trp Gly Gln 50 55 60 ccc cat gga ggt ggc tgg ggc cag cct cat gga ggt ggc tgg ggc cag 240 Pro His Gly Gly Gly Trp Gly Gln Pro His Gly Gly Gly Trp Gly Gln 65 70 75 cct cat gga ggt ggc tgg ggt cag ccc cat ggt ggt ggc tgg gga cag 288 Pro His Gly Gly Gly Trp Gly Gln Pro His Gly Gly Gly Trp Gly Gln 80 85 90 cca cat ggt ggt gga ggc tgg ggt caa ggt ggt acc cac ggt caa tgg 336 Pro His Gly Gly Gly Gly Trp Gly Gln Gly Gly Thr His Gly Gln Trp 95 100 105 110 aac aaa ccc agt aag cca aaa acc aac atg aag cat gtg gca gga gct 384 Asn Lys Pro Ser Lys Pro Lys Thr Asn Met Lys His Val Ala Gly Ala 115 120 125 gct gca gct gga gca gtg gta ggg ggc ctt ggt ggc tac atg ctg gga 432 Ala Ala Ala Gly Ala Val Val Gly Gly Leu Gly Gly Tyr Met Leu Gly 130 135 140 agt gcc atg agc agg cct ctt ata cat ttt ggc agt gac tat gag gac 480 Ser Ala Met Ser Arg Pro Leu Ile His Phe Gly Ser Asp Tyr Glu Asp 145 150 155 cgt tac tat cgt gaa aac atg cac cgt tac ccc aac caa gtg tac tac 528 Arg Tyr Tyr Arg Glu Asn Met His Arg Tyr Pro Asn Gln Val Tyr Tyr 160 165 170 agg cca gtg gat cgg tat agt aac cag aac aac ttt gtg cat gac tgt 576 Arg Pro Val Asp Arg Tyr Ser Asn Gln Asn Asn Phe Val His Asp Cys 175 180 185 190 gtc aat atc aca gtc aag gaa cac aca gtc acc acc acc acc aag ggg 624 Val Asn Ile Thr Val Lys Glu His Thr Val Thr Thr Thr Thr Lys Gly 195 200 205 gag aac ttc acc gaa act gac atc aag atg atg aag cga gtg gtg gag 672 Glu Asn Phe Thr Glu Thr Asp Ile Lys Met Met Lys Arg Val Val Glu 210 215 220 caa atg tgc att acc cag tac cag aga gaa tcc cag gct tat tac caa 720 Gln Met Cys Ile Thr Gln Tyr Gln Arg Glu Ser Gln Ala Tyr Tyr Gln 225 230 235 cga ggg gca agt gtg atc ctc ttc tct tcc cct cct gtg atc ctc ctc 768 Arg Gly Ala Ser Val Ile Leu Phe Ser Ser Pro Pro Val Ile Leu Leu 240 245 250 atc tct ttc ctc att ttt ctc ata gta gga tag gggcaacctt cctgttttca 821 Ile Ser Phe Leu Ile Phe Leu Ile Val Gly 255 260 ttatcttctt aatctttacc aggttggggg agggagt 858 32 264 PRT Bos taurus 32 Met Val Lys Ser His Ile Gly Ser Trp Ile Leu Val Leu Phe Val Ala 1 5 10 15 Met Trp Ser Asp Val Gly Leu Cys Lys Lys Arg Pro Lys Pro Gly Gly 20 25 30 Gly Trp Asn Thr Gly Gly Ser Arg Tyr Pro Gly Gln Gly Ser Pro Gly 35 40 45 Gly Asn Arg Tyr Pro Pro Gln Gly Gly Gly Gly Trp Gly Gln Pro His 50 55 60 Gly Gly Gly Trp Gly Gln Pro His Gly Gly Gly Trp Gly Gln Pro His 65 70 75 80 Gly Gly Gly Trp Gly Gln Pro His Gly Gly Gly Trp Gly Gln Pro His 85 90 95 Gly Gly Gly Gly Trp Gly Gln Gly Gly Thr His Gly Gln Trp Asn Lys 100 105 110 Pro Ser Lys Pro Lys Thr Asn Met Lys His Val Ala Gly Ala Ala Ala 115 120 125 Ala Gly Ala Val Val Gly Gly Leu Gly Gly Tyr Met Leu Gly Ser Ala 130 135 140 Met Ser Arg Pro Leu Ile His Phe Gly Ser Asp Tyr Glu Asp Arg Tyr 145 150 155 160 Tyr Arg Glu Asn Met His Arg Tyr Pro Asn Gln Val Tyr Tyr Arg Pro 165 170 175 Val Asp Arg Tyr Ser Asn Gln Asn Asn Phe Val His Asp Cys Val Asn 180 185 190 Ile Thr Val Lys Glu His Thr Val Thr Thr Thr Thr Lys Gly Glu Asn 195 200 205 Phe Thr Glu Thr Asp Ile Lys Met Met Lys Arg Val Val Glu Gln Met 210 215 220 Cys Ile Thr Gln Tyr Gln Arg Glu Ser Gln Ala Tyr Tyr Gln Arg Gly 225 230 235 240 Ala Ser Val Ile Leu Phe Ser Ser Pro Pro Val Ile Leu Leu Ile Ser 245 250 255 Phe Leu Ile Phe Leu Ile Val Gly 260 

We claim:
 1. A method of making cattle resistant to bovine spongioform encephalopathy, comprising: a) providing a modifying composition comprising a DNA fragment having a length of between 100 and 1000 bp and having essentially the sequence of the bovine PrP gene modified to prevent translation of the PrP protein; b) introducing the modifying composition into a somatic cell from a cow or bull and culturing the cell to produce a cell having a modified PrP gene; c) isolating said modified cell from cells having an unmodified PrP gene; and d) transferring a nucleus from said isolated cell into a competent bovine germ-line cell and generating a founder cow or bull from the germ-line cell.
 2. The method of claim 1, wherein the DNA fragment is single stranded and the modifying composition is substantially free of DNA complementary to the fragment.
 3. The method of claim 2, wherein the length of the single stranded fragment is between 200 and 800 nt.
 4. The method of making cattle resistant to bovine spongioform encephalopathy which comprises the method of claim 2, and the further step of interbreeding a founder cow and a founder bull.
 5. The method of claim 4, wherein the length of the single stranded fragment is between 200 and 800 nt.
 6. The method of claim 2, wherein the modified cell is isolated using coupled detection.
 7. A composition comprising a single stranded DNA fragment having a length of between 100 and 1000 nt and having essentially the sequence of the bovine PrP gene modified to prevent translation of the PrP protein, wherein the composition is substantially free of DNA complementary to the fragmen.
 8. The composition of claim 7, wherein the length of the single stranded fragment is between 400 and 800 nt.
 9. A method of making cattle resistant to bovine spongioform encephalopathy, comprising: a) providing a modifying composition comprising a DNA fragment having a length of between 100 and 1000 bp and having essentially the sequence of the bovine PrP gene modified to encode a dominant disease-resistant PrP protein; b) introducing the modifying composition into a somatic cell from a cow or bull and culturing the cell to produce a cell having a modified PrP gene; c) isolating said modified cell from cells having an unmodified PrP gene; and d) transferring a nucleus from said isolated cell into a competent bovine germ-line cell and generating a founder cow or bull from the germ-line cell.
 10. The method of claim 9, wherein the dominant disease-resistant PrP protein contains a glutamine-to-arginine substitution at amino acid
 178. 11. The method of claim 9, wherein the DNA fragment is single stranded and the modifying composition is substantially free of DNA complementary to the fragment.
 12. The method of claim 11, wherein the length of the single stranded fragment is between 200 and 800 nt.
 13. The method of making cattle resistant to bovine spongioform encephalopathy which comprises the method of claim 11, and the further step of interbreeding a founder cow and a founder bull.
 14. The method of claim 13, wherein the length of the single stranded fragment is between 200 and 800 nt.
 15. The method of claim 11, wherein the modified cell is isolated using coupled detection.
 16. A composition comprising a single stranded DNA fragment having a length of between 100 and 1000 nt and having essentially the sequence of the bovine PrP gene modified to encode a dominant disease-resistant PrP protein, wherein the composition is substantially free of DNA complementary to the fragment.
 17. The composition of claim 16, wherein the length of the single stranded fragment is between 400 and 800 nt.
 18. A method of testing for bovine spongioform encephalopathy resistance in the offspring of a cow and a bull comprising: a) obtaining a nucleic acid sample from an offspring of a cow and a bull, wherein at least one parent carries a modified PrP gene that confers resistance to bovine spongioform encephalopathy; and b) determining whether the modified PrP gene is present in the sample;
 19. The method of claim 17, which further comprises determining whether the wild-type PrP gene is present in the sample. 